A list of all the patches available for the game can be found here.
The latest patch available is v1.7.
The GOG.com version of game includes latest patch, and is compatibile with modern systems
General Improvement Mod (GIM), community made, fixing some issues on modern systems
HKEY_CURRENT_USER\SOFTWARE\Bullfrog Productions Ltd\Dungeon Keeper II\Configuration\Player
The main menu (and anything associated with that area) has a generally poor frame rate. It is most likely caused by the display of the menu or overlay.
Known issues include startup crash, a black cover over what should be visible, and in-game crashes. The following steps fix most of these problems.
Copy unofficial patch "GIM_v1.05" (latest version, download), and run game through DKII-DX.exe (set compatibility to windows 2000).
Extract the files within DK2Editor.zip to <path-to-game>\Data\editor instead of the folder described in the readme.